fix(sandbox): bake project source synchronizer

.github/workflows/build-snapshot.yml

@@ -144,6 +144,8 @@ jobs:
             npm --version
             pnpm --version
             python3 --version
+            test -x /opt/cheatcode/project-source-sync.py
+            python3 -c "import ast,pathlib;ast.parse(pathlib.Path(\"/opt/cheatcode/project-source-sync.py\").read_text())"
             code-server --version
             "$CHROME_PATH" --version
             libreoffice --version

apps/agent-worker/README.md

@@ -152,6 +152,9 @@ webpack compilation even after the listening socket opens. A baked Python synchr
 full refresh on every process start and mirrors subsequent writes and deletions within one second,
 including shell-based edits. The local source, dependency tree, and build cache are disposable;
 wake and restart reconstruct them from the durable project without changing the Files surface.
+The immutable sandbox exposes that synchronizer as the root-owned
+`/opt/cheatcode/project-source-sync.py` helper, keeping Worker-to-sandbox command arguments small
+and making the snapshot the source of truth for executable sandbox runtime code.
 Direct pnpm commands use that same native-disk source as a transaction: the runtime snapshots the
 durable source, executes pnpm locally, and copies only command-produced source changes back after
 verifying that the corresponding durable paths did not change concurrently. Long-running pnpm

apps/agent-worker/src/durable-objects/project-sandbox-local-source.ts

@@ -1,218 +1,7 @@
 import { shellQuote } from "../sandbox-support";
 import type { ProjectLocalRuntime } from "./project-sandbox-package-runtime";
 
-const LOCAL_SOURCE_SYNC_SCRIPT = `
-import hashlib
-import json
-import os
-import shutil
-import sys
-import time
-
-IGNORED_DIRS = {".expo", ".next", ".turbo", "build", "coverage", "dist", "node_modules", "out"}
-LOCAL_ONLY_NAMES = IGNORED_DIRS | {"next-env.d.ts"}
-LOCK_STALE_SECONDS = 15 * 60
-
-def remove_path(path):
-    if os.path.isdir(path) and not os.path.islink(path):
-        shutil.rmtree(path)
-    elif os.path.lexists(path):
-        os.unlink(path)
-
-def sync_link(source, target):
-    link = os.readlink(source)
-    if os.path.islink(target) and os.readlink(target) == link:
-        return
-    remove_path(target)
-    os.symlink(link, target)
-
-def sync_file(source, target, force):
-    source_stat = os.stat(source, follow_symlinks=False)
-    try:
-        target_stat = os.stat(target, follow_symlinks=False)
-    except FileNotFoundError:
-        target_stat = None
-    changed = (
-        force
-        or target_stat is None
-        or not os.path.isfile(target)
-        or source_stat.st_size != target_stat.st_size
-        or source_stat.st_mtime_ns > target_stat.st_mtime_ns
-    )
-    if changed:
-        remove_path(target)
-        shutil.copyfile(source, target, follow_symlinks=False)
-
-def sync_directory(source, target, force=False):
-    if os.path.lexists(target) and not os.path.isdir(target):
-        remove_path(target)
-    os.makedirs(target, exist_ok=True)
-    source_names = set()
-    for entry in os.scandir(source):
-        if entry.name in IGNORED_DIRS:
-            continue
-        source_names.add(entry.name)
-        destination = os.path.join(target, entry.name)
-        try:
-            if entry.is_symlink():
-                sync_link(entry.path, destination)
-            elif entry.is_dir(follow_symlinks=False):
-                sync_directory(entry.path, destination, force)
-            elif entry.is_file(follow_symlinks=False):
-                sync_file(entry.path, destination, force)
-        except FileNotFoundError:
-            continue
-    for entry in os.scandir(target):
-        if entry.name not in source_names and entry.name not in LOCAL_ONLY_NAMES:
-            remove_path(entry.path)
-
-def digest(path):
-    value = hashlib.sha256()
-    with open(path, "rb") as source:
-        for chunk in iter(lambda: source.read(1024 * 1024), b""):
-            value.update(chunk)
-    return value.hexdigest()
-
-def tree_state(root):
-    state = {}
-    if not os.path.isdir(root):
-        return state
-    for current, dir_names, file_names in os.walk(root, topdown=True, followlinks=False):
-        dir_names[:] = sorted(name for name in dir_names if name not in IGNORED_DIRS)
-        relative_root = os.path.relpath(current, root)
-        for name in dir_names:
-            path = os.path.join(current, name)
-            relative = os.path.normpath(os.path.join(relative_root, name))
-            if os.path.islink(path):
-                state[relative] = ["link", os.readlink(path)]
-            else:
-                state[relative] = ["dir"]
-        for name in sorted(file_names):
-            if name in LOCAL_ONLY_NAMES:
-                continue
-            path = os.path.join(current, name)
-            relative = os.path.normpath(os.path.join(relative_root, name))
-            if os.path.islink(path):
-                state[relative] = ["link", os.readlink(path)]
-            else:
-                state[relative] = ["file", digest(path)]
-    return state
-
-def package_lock_active(lock_path):
-    try:
-        age = time.time() - os.path.getmtime(lock_path)
-    except FileNotFoundError:
-        return False
-    if age <= LOCK_STALE_SECONDS:
-        return True
-    try:
-        os.unlink(lock_path)
-    except FileNotFoundError:
-        pass
-    return False
-
-def wait_for_preview(lock_path, busy_path):
-    deadline = time.time() + 30
-    while os.path.exists(busy_path):
-        if time.time() >= deadline:
-            raise TimeoutError("local source mirror did not quiesce")
-        time.sleep(0.05)
-
-def preview_sync(source, target, mode, lock_path, busy_path):
-    force = mode == "preview-once"
-    while True:
-        if package_lock_active(lock_path):
-            if force:
-                time.sleep(0.05)
-                continue
-            time.sleep(0.25)
-            continue
-        os.makedirs(os.path.dirname(busy_path), exist_ok=True)
-        with open(busy_path, "w", encoding="utf-8"):
-            pass
-        try:
-            if package_lock_active(lock_path):
-                continue
-            sync_directory(source, target, force)
-        finally:
-            try:
-                os.unlink(busy_path)
-            except FileNotFoundError:
-                pass
-        if force:
-            return
-        time.sleep(0.75)
-
-def prepare(source, target, lock_path, busy_path, baseline_path):
-    os.makedirs(os.path.dirname(lock_path), exist_ok=True)
-    with open(lock_path, "w", encoding="utf-8") as lock:
-        lock.write(str(time.time()))
-    try:
-        wait_for_preview(lock_path, busy_path)
-        sync_directory(source, target, True)
-        with open(baseline_path, "w", encoding="utf-8") as baseline:
-            json.dump(tree_state(target), baseline, sort_keys=True, separators=(",", ":"))
-    except Exception:
-        cleanup(lock_path, baseline_path)
-        raise
-
-def copy_state(source_root, target_root, relative, state):
-    source = os.path.join(source_root, relative)
-    target = os.path.join(target_root, relative)
-    kind = state[0]
-    if kind == "dir":
-        if os.path.lexists(target) and not os.path.isdir(target):
-            remove_path(target)
-        os.makedirs(target, exist_ok=True)
-        return
-    os.makedirs(os.path.dirname(target), exist_ok=True)
-    if kind == "link":
-        sync_link(source, target)
-        return
-    if os.path.isdir(target) or os.path.islink(target):
-        remove_path(target)
-    shutil.copyfile(source, target, follow_symlinks=False)
-
-def cleanup(lock_path, baseline_path):
-    for path in (baseline_path, lock_path):
-        try:
-            os.unlink(path)
-        except FileNotFoundError:
-            pass
-
-def commit(source, target, lock_path, baseline_path):
-    try:
-        with open(baseline_path, encoding="utf-8") as baseline_file:
-            baseline = json.load(baseline_file)
-        local = tree_state(target)
-        durable = tree_state(source)
-        changed = sorted(path for path in set(baseline) | set(local) if baseline.get(path) != local.get(path))
-        conflicts = [
-            path
-            for path in changed
-            if durable.get(path) != baseline.get(path) and durable.get(path) != local.get(path)
-        ]
-        if conflicts:
-            raise RuntimeError("durable project changed during package command: " + ", ".join(conflicts[:8]))
-        for relative in sorted((path for path in changed if path not in local), key=lambda value: value.count(os.sep), reverse=True):
-            remove_path(os.path.join(source, relative))
-        for relative in sorted((path for path in changed if path in local), key=lambda value: value.count(os.sep)):
-            copy_state(target, source, relative, local[relative])
-    finally:
-        cleanup(lock_path, baseline_path)
-
-mode, source, target, lock_path, busy_path, baseline_path = sys.argv[1:7]
-if mode in {"preview-once", "preview-loop"}:
-    preview_sync(source, target, mode, lock_path, busy_path)
-elif mode == "package-prepare":
-    prepare(source, target, lock_path, busy_path, baseline_path)
-elif mode == "package-commit":
-    commit(source, target, lock_path, baseline_path)
-elif mode == "package-abort":
-    cleanup(lock_path, baseline_path)
-else:
-    raise ValueError("unknown local source synchronization mode")
-`;
+const LOCAL_SOURCE_SYNC_BINARY = "/opt/cheatcode/project-source-sync.py";
 
 function runtimeStatePaths(runtime: ProjectLocalRuntime): {
   baselinePath: string;
@@ -232,9 +21,7 @@ export function localSourceSyncCommand(
 ): string {
   const { baselinePath, busyPath, lockPath } = runtimeStatePaths(runtime);
   return [
-    "python3",
-    "-c",
-    LOCAL_SOURCE_SYNC_SCRIPT,
+    LOCAL_SOURCE_SYNC_BINARY,
     mode,
     runtime.workspaceDir,
     runtime.localSourceDir,

infra/containers/sandbox/README.md

@@ -95,6 +95,11 @@ restored from the reviewed package store after a sandbox replacement. Expo uses
 `default` alias. These locks prevent a snapshot rebuild from resolving a different
 dependency tree while the application source stays unchanged.
 
+The root-owned `/opt/cheatcode/project-source-sync.py` helper is the single runtime
+boundary between persistent project source and the native-disk project mirror. It is
+baked and syntax-checked with the immutable image so Workers invoke a short, bounded
+command instead of transporting executable source through sandbox command arguments.
+
 Open VSX currently publishes Parquet Viewer 3.1.0 with vulnerable Thrift and WebSocket
 runtimes. The image keeps the extension feature but replaces those two runtime packages
 with the exact, lockfile-pinned versions in `extension-overrides/parquet-viewer/` and